Related to the confirmation bias, an example of "tunnel vision" would be:

Related to the confirmation bias, an example of "tunnel vision" would be a new product launching and being judged prior to even trying the product. If people are judging a product based on something they think or hear before trying it they have bias towards it. Tunnel vision refers to having a set mindset even when there are other factors around that can change it, but you're stuck on that same thought. 

Basically create a schedule on what you need to study and stick with it